Magnetostriction
Magnetostriction is the deformation of a magnetic material when it is magnetized or more generally when its magnetic state is modified. The opposite effect also exists: a mechanical stress modifies the magnetic state. It should also be noted that magnetostrictive materials are not only limited to ferromagnetics with a direct influence of the magnetic field but also to antiferromagnetics.
The topicality of magnetostriction studies is related to its impacts on the understanding of the fundamental properties of magnetic materials and industrial applications. On the one hand, magnetostriction provides information on magnetic exchange, it can be used to modify the magnetic anisotropy of materials and to control their magnetic state. On the other hand, materials with such properties are attractive for actuators, sensors, microsystems.
OPTIMAG is equipped with an optical deflectometry measuring bench that provides access to the magneto-elastic coefficients: the angular deflections (bending and torsion) of a laser beam reflected by the sample are measured when it is subjected to a magnetic field. This "direct" method is completed by a "reverse" method, the magnetic state of the sample is studied when it is subjected to stress. [J. Magn. Magn. Magn. Mat. 2010].
Magnetostriction cycles can be used as a tool of choice to complement "classical" magnetometry (VSM) techniques: magnetostriction can be used as a magnetometer to study the reversal processes of magnetization in samples with little or no magnetization (in the case of antiferromagnetics).
Knowledge of magnetostriction is essential in extrinsic multiferroic materials (see also this section) in which a piezoelectric material and a ferromagnetic are combined since electrical control is achieved through stress. [Coll. Louis Néel Paris 2017 ].
Ongoing thesis
Financing Brittany Region / University of Brest - Co-badging with the Physics Department of Johannesburg - South Africa - Walaa Jahjah "MultIferroic Intrinsic and Extrinsic NanOstructures: Towards Electrical Control of Magnetic Properties (NOMINATED)".
Collaborations
University of Johanesburg
CEMES Toulouse
Institute of Physics of Rennes
